1. Field of the Invention
The present invention relates to an open-type compressor which is built into an air conditioner, refrigerating machine, or the like.
2. Description of the Related Art
Conventionally, air conditioners, refrigerating machines, and the like employ a compressor such as a scroll compressor.
Generally, in scroll compressors, a fixed scroll member which has a base plate and a spiral portion, and a revolving scroll member which also has a base plate and a spiral portion face each other in a manner such that their spiral portions are engaged with each other with a phase difference of 180xc2x0, and compression chambers are formed between the scroll members. According to the rotation of the shaft, the revolving scroll member revolves around the axis of the fixed scroll member, so that the capacities of the compression chambers gradually reduce while the positions of the compression chambers gradually move from the peripheral side to the center side of the spiral portions, thereby compressing the relevant gas.
FIG. 2 shows a conventional open-type scroll compressor applied to an air conditioner which is built into a vehicle. In a closed housing H consisting of a front housing 4 and a rear housing 5, a scroll compression mechanism C is contained, and an electromagnetic clutch MC is provided at the outside of an end portion of the front housing 4. The scroll compression mechanism C and the electromagnetic clutch MC are directly coupled and joined with each other via a shaft 6, an end of which protrudes from the front housing 4.
The shaft 6 is rotatably supported by a main bearing 7a and a sub bearing 7b, where these bearings are contained in the front housing 4. Here, the main bearing 7a is a needle bearing consisting of an outer ring and a plurality of roller-shaped needles, while the sub bearing 7b is a ball bearing consisting of a plurality of balls between outer and inner rings.
Between the main bearing 7a and the sub bearing 7b, a seal member 34 made of an elastic rubber material is provided, which is also contained in the front housing 4. Owing to the seal member 34, leakage of gas or lubricating oil inside the housing H can be prevented. Additionally, the motion of the seal member 34 in the axial direction of the front housing 4 is prohibited by a stopper 34a. 
In the above-explained compressor, when power is transmitted from an external power source (not shown) via a belt to the electromagnetic clutch MC, the shaft 6 rotates and drives the scroll compression mechanism C, so that a refrigerant gas is introduced from a suction hole (not shown) into the closed housing H. This introduced gas is compressed by the scroll compression mechanism C and discharged through a discharge hole (not shown) to the outside of the housing H.
Below, the electromagnetic clutch MC will be explained. An end portion of the shaft 6 of the above-explained scroll compressor is inserted through an attachment hole 41a of an armature plate 41. The armature plate 41, which is a constituent of the electromagnetic clutch MC, is fastened by using a nut 42 which is screwed and fit onto the end portion of the shaft 4.
A rotor 43, which is also a constituent of the electromagnetic clutch MC, is rotatably attached to the front housing 4, and the rotor 43 rotates by receiving power which is transmitted from an external power source (not shown) via a V-belt (not shown). When a coil (not shown) contained in the rotor 43 of the electromagnetic clutch MC is excited (or energized) by receiving a supplied current, the armature plate 41 is attracted to the rotor 43, so that the rotational power of the rotor 43 is transmitted to the shaft 6.
As for a clearance xcex4 between the rotor 43 and the armature plate 41 which are constituents of the electromagnetic clutch MC, if the clearance xcex4 set at the time of assembly is too large, the rotor 43 and the armature plate 41 do not contact each other when the coil is excited, so that the shaft 6 cannot be driven. Conversely, if the clearance xcex4 set at the time of assembly is too small, the armature plate 41 will always contact the rotor during rotation, so that an abnormal sound or abnormal abrasion due to heat (generated by continuous contact) may occur. Therefore, in the assembly, a specific clearance xcex4 (approximately 0.1 to 0.3 mm) must be set between the rotor 43 and the armature plate 41. Accordingly, in this compressor, a shim 56 for adjusting the clearance is placed between the armature plate 41 and the inner ring of the sub bearing 7b. 
Additionally, in the structure of this compressor, the outer ring of the sub bearing 7b contacts a step portion 4b formed in the front housing 4. That is, even if a load for forcing the shaft 6 back towards the inside of the housing H acts via the armature plate 41 after assembly, the movement of the outer ring of the sub bearing 7b and the front housing 4 is restricted, thereby preventing the clearance xcex4 from being too small.
Furthermore, the inner ring of the sub bearing 7b contacts a stopper 6b at the compression mechanism side of the sub bearing 7b, where the stopper 6b is fit into a groove 6c which is formed on the shaft 6. Accordingly, even if a load for extracting the shaft 6 from the housing H acts via the armature plate 41 after assembly, the movement of the shaft 6 and the inner ring of the sub bearing 7b is restricted, thereby preventing the clearance xcex4 from being too large.
In the scroll compressor having the above structure, in the first step of attaching the shaft 6 to the front housing 4, the main bearing 7a is pressed into the front housing 4, and the shaft 6 is made to fall into the front housing 4 which is positioned in a manner such that the side which will contact the rear housing 5 is set to be the top side. In the next step, the position (or orientation) of the front housing 4 is inverted, and the seal member 34 is fit around the shaft 6 and onto the step portion 4a, where the step portion 4a is formed in an inner-peripheral face of the front housing 4. The stopper 34a is then attached.
In the following step, the stopper 6b is attached to the shaft 6, and the sub bearing 7b is pressed into the inner-peripheral face of the front housing 4, and simultaneously, the sub bearing 7b is fit onto the step portion 4b which is formed in the inner-peripheral face of the front housing 4.
However, in the above-explained compressor, the main bearing 7a employs a needle bearing consisting of an outer ring and a plurality of roller-shaped needles. Therefore, when the front housing 4 is inverted after the insertion of the shaft 6 into the front housing 4, the shaft 6 may fall from the front housing 4 because the main bearing 7a has no capability of controlling the position of the shaft 6 in its axial direction. Accordingly, improved working conditions have been desired.
In addition, the stoppers 34a and 6b are positioned very deep in the inner-peripheral side of the front housing 4. Therefore, various relevant parts are required, and thus the assembling process is complicated and difficult.
Also in the compressor, the stopper 6b is fit into the groove 6c which is formed on the shaft 6, so as to determine the clearance xcex4 of the electromagnetic clutch MC. However, if the stopper 6b is not appropriately fit into the groove 6c (i.e., having play or the like), the clearance xcex4 of the electromagnetic clutch MC is not fixed. In order to solve this problem, the stopper 6b and groove 6c must be very accurately processed.
In addition, during the checking or repair of the above compressor which has the stopper 6b on the shaft 6, when the shaft 6 is extracted from the front housing 4, a portion of the stopper 6b is caught by the seal member 34; thus, it is very difficult to exchange the current shaft for another.
In consideration of the above circumstances, an object of the present invention is to provide a compressor which can be assembled under desirable working conditions at a low cost.
Therefore, the present invention provides a compressor comprising:
a first housing;
a shaft having an end portion which protrudes from the first housing and which is rotated by a driving source;
a compression mechanism provided at the side of the other end portion of the shaft for compressing and discharging a gas which is absorbed into the compression mechanism due to the rotation of the shaft;
a second housing for containing the compression mechanism, the second housing being joined with the first housing; and
first and second rolling bearings for rotatably supporting the shaft, wherein the first and second rolling bearings are positioned in an insertion hole which is formed in the first housing and into which the shaft is inserted, and wherein:
the first rolling bearing for permitting the movement of the shaft in the axial direction of the shaft is inserted into the first housing from the side where the compression mechanism is to be provided;
the second rolling bearing for restricting the movement of the shaft in the axial direction of the shaft is inserted into the first housing from the other side where the driving source is to be provided; and
the shaft is inserted into the first housing from the side where the compression mechanism is to be provided,
the compressor further comprising:
a seal member provided between the first and second rolling bearings for sealing an area between the insertion hole and the shaft, wherein the seal member is inserted into the insertion hole of the first housing from the side where the compression mechanism is to be provided before the shaft is inserted into the insertion hole.
According to the above compressor, the seal member is provided in advance before the shaft is inserted; thus, the inserted shaft can be supported by the elastic seal member. Therefore, even when the first housing after this process is inverted so as to insert and build other components (to be assembled) from the other side, it is possible to prevent the shaft (inserted into the insertion hole) from falling from the housing, thereby improving the working conditions.
Preferably, a protrusion is formed in a circumferential direction on an inner peripheral face of the insertion hole of the first housing; and the seal member is inserted into the insertion hole in a manner such that the seal member is positioned between the protrusion and the compression mechanism.
Accordingly, the position of the seal member in the first housing in the axial direction of the shaft is restricted by the protrusion; thus, a stopper or the like for holding the seal member is unnecessary, thereby improving the working conditions for assembly and reducing the number of parts and the costs.
It is possible that:
the second rolling bearing has inner and outer rings, and the position of the second rolling bearing with respect to the first housing in the axial direction of the shaft is determined by making the outer ring contact a side face of the protrusion; and
the shaft has a step portion formed at a head portion of the shaft, and the position of the shaft with respect to the second rolling bearing in the axial direction of the shaft is determined by making the step portion contact the inner ring.
Accordingly, the positioning is performed in a manner such that the step portion of the shaft contacts the second rolling bearing, where the second rolling bearing contacts the protrusion so as to determine its position with respect to the first housing. Therefore, the position of the shaft with respect to the first housing can be reliably and accurately determined via the second bearing; thus, a stopper or the like for positioning the shaft is unnecessary, thereby improving the working conditions for assembly and reducing the number of parts. In addition, during checking or repair, the shaft can be easily extracted, thereby improving the working conditions.
Typically, the compressor is a scroll compressor.